Electrolytic strip-marking roll



NOV. 17, 1970 J BEEMER ETAL 3,541,083

ELECTROLYTIC STRIP-MARKING ROLL s Sheets-Sheet 1 FiledFeb. 21. 1968:

. INVENTORS. JAMES 6. JEEMER LEW/5 c. mum 0V5 BY M M6242;

Pig 2 ATTORNEY NOV. 17, 1970 BEEMER ETAL 3,541,083

V EL TR Filed Feb. '21, 1968" 3 Sheets-Sheet 2 ////{//4 'w i I l $51 i M I M INVENTORS.

- JAMES a. assume L EW/S c. TOMP/(INS l iY ATTORNEY Nov. 17, 1970 J. G. BEEMER ETAL 3,541,083

ELECTROLYTIC STRIP-MARKING ROLL I Filed Feb. 21, 1968 s Sheets- Sheet 3' #4455 6. 5554/5? LEW/5 c. TWP/(0V5 ATTORNEY INVBNTORS.

United States Patent US. Cl. 204--224 2 Claims ABSTRACT OF THE DISCLOSURE A roll for electrolytically etching metal strip and the method for making .such roll which includes providing a cylindrical roll body made of electrically conductive material, attaching a plurality of short lengths of wire to the circumference of the roll body in radially projecting fashion arranged in the form of a desired marking pattern, and then forming a sleeve of electrically insulating materialaround the roll body with the lengths of wires projecting through the sleeve. After the roll has thus been made, it may be immersed in a solvent solution to dissolve the wires projecting from the roll body through the insulating sleeve so as to form etching holes in the sleeve; or the ends of the wires may be finished to a flush condition with the insulating sleeve so that the wire ends can function as etching means.

The present invention relates generally to the marking of continuous metal strip and has as its primary object the provision of an improved roll for etfecting electrolytic etching of a desired pattern of marking on continuous steel strip and the method of manufacturing such-roll.

In recent years can makers have demanded required improved means for identifying the source of tin plate in samples of their finished product as an aid in their quality control programs. As a result, it has become an industrywide practice for tin plate producers to etch a characteristic repetitive pattern of dots on all tin plate strip prior to tin coating. The pattern is imperceptible to the unaided eye after tin coating, but may be revealed when necessary by de-tinning the tinned product. Each tin plate producer has its own distinctive pattern which serves as its brand.

It is, accordingly, the primary object of our invention to provide an improved electrolytic strip-marking roll and a method of manufacturing the roll which involves providing a cylindrical roll body of electrically conductive material, attaching to the circumference of such roll body a plurality of radially projecting short lengths of wire arranged in the form of a desired mark, and then applying a sleeve of electrically insulating material around the roll body in such a manner that the wire lengths project beyond the sleeve of insulating material.

As a corollary to the above object it is another object of our invention to provide an improved marking roll and method of manufacturing as set forth above including the additional step of either immersing the roll in a solvent solution to dissolve the wires after the insulating sleeve has been applied around the roll body or finishing the ends of the wires to a flush condition with theinsulating sleeve.

These and other objects will become more apparent after referring to the following specification and attached drawings in which:

FIG. 1 is a schematic elevational view of the entrance end of an electrolytic tinning line having the marking roll of the invention installed therein;

FIG. 2 is an end view looking at the entrance end of the electrolytic tinning line shown in FIG. 1;

FIG. 3 is a longitudinal sectional view of the marking roll of the invention prior to dissolving the wire lengths attached to the roll body or finishing the ends of the wire lengths to make them flush with the insulating sleeve of the roll body;

FIG. 4 is an enlarged sectional view taken substantially along the line IV-IV of FIG. 3;

FIG. 5 is a partial view similar to FIG. 3 illustrating the roll after the radial wire lengths have been dissolved from the circumference of the roll so as to form etching holes in the insulating sleeve;

FIG. 6 is a sectional view taken along the line VI-VI of FIG. 5; and

FIG. 7 is a partial view similar to FIG. 4 showing the ends of the wire lengths after they have been finished to' a flush condition with the insulating sleeve.

Referring more particularly to the drawings, FIG. 1 schematically shows the entrance end of an electrolytic tinning line having the marking roll of the invention installed therein above the pickling tank 2 of the line which contains a sulphuric acid solution for pickling steel strip prior to tinning. A conductor roll 4 is journaled above the tank 2 and a sink roll 6 is rotatably mounted inside the tank. The marking roll of the invention, designated generally by reference character 8, is rotatably mounted above the tank 2 adjacent the conductor roll 4. A pulley 10 may be provided on the shaft of the marking roll whereby the marking roll can be driven by means of a V-belt drive 12 connected to a motor (not shown). In operation, strip S to be tinned is passed around the conductor roll 4, into the tank 2, around the sink roll 6 and then out of the tank 2, around the marking roll 8 and then back into the tank to complete the pickling operation. After leaving the pickling tank the strip is rinsed and then electrolytically tinned in a conventional manner.

The construction just described is conventional except for the novel marking roll 8 of our invention, the details of which will now be described.

As shown in FIG. 3, the improved marking roll of the invention consists of a cylindrical roll body 14, end-bells 16, shaft 18 and a commutator ring 20 disposed on one end of the shaft 18. The metal for these parts may be any electrically conductive metal resistant to sulphuric acid and is preferably a Cb-stabilized stainless alloy containing 20% Cr, 29% Ni. Small blind holes 24, approximately 0.040 inch in diameter and about ,6 inch deep are drilled in the surface of the roll body 14 arranged in the desired marking pattern. Short lengths of wire 26 made of the same material as the roll body and having a diameter to snugly fit the holes 24 are inserted in the holes. A tight fit for the wire lengths is desired in order to insure good electrical contact. The length of the wires should be slightly greater than the thickness of the insulating sleeve 28 which will be subsequently applied to the roll body.

The insulating sleeve 28 may be made of plastic or other electrically insulating material but is preferably made of a ceramic material. If a plastic material such as Teflon is used in the sleeve 28, its thickness should be approximately /2 .inch. For a ceramic sleeve, a thickness of not more than 0.030 inch is sufficient. The ceramic sleeve may be formed by applying a ceramic coating to the roll body after the wire lengths 26 have been attached. The ceramic material making up the sleeve 28 may be applied by plasma arc-flame spraying, the technique of which is described in the ASM Handbook, volume II, page 587 et seq. The ceramic material is preferably aluminum oxide or a mixture of aluminum and chromium oxides; however, any electrically insulating and abrasive-acid-resistant material can be used.

After the insulating sleeve, of either plastic or ceramic material, has been applied, the wire lengths 26 are clipped and the outer surface of the sleeve-equipped roll is ground to a smooth surface. After the roll is ground the ends of the wire lengths 26 are flush with the outer surface of the insulatingsleeve, as best shown in FIG. 7.

An electrolytic circuit for etching with the marking roll 8 of our invention may be provided in a conventional manner such as by passing an electrolytic current from a DC generator 30 through brushes 32 to a collector ring 34 on the shaft of the conductor roll 4. The current then passes along the strip S into the sulphuric acid solution in the pickling tank 2 and then to the marking roll 8 where electrolysis occurs. The etching electrolyte, which in this instance consists simply of the thin film of pickling solution which is confined between the surface of the marking roll and the surface of the strip facing the roll, etches the strip surface as it passes over the flush ends of the wire lengths 26. The current then flows out of the marking roll through the commutator ring 20 and the brushes 36 attached thereto back to the generator. In the electrolytic circuit just described the strip S is anodic and the marking roll 8 and the wire lengths 26 are cathodic.

In a modified embodiment of the method of th invention, the wire lengths attached to the roll body 14' are made of aluminum. The insulating sleeve 28', which is preferably made of ceramic material, is applied over the body roll after the aluminum Wire lengths have been attached thereto. Following the application of the insulating sleeve 28' to the roll body, the roll is placed in normal service above the pickling tank. When the roll is placed into service, the aluminum wires are dissolved by the sulphuric acid solution carried in contact therewith by the strip. It will be noted that, if desired, the roll may be immersed in a solvent to dissolve the aluminum wires prior to being placed in service. Dissolving of the aluminum wires leaves holes 40 in the ceramic insulating sleeve 28 which are arranged in the pattern of the desired marking.

In this arrangement the surface of the strip passing overthe marking roll is anodic with Iespectto thesurface of the roll body 14 and is etched by the flow of current therebetween, the etching effect being restricted to the area defined by the holes 40 in the insulating sleeve 28'. The electrolyte in the process is the sulphuric acid solution carried out of the pickling tank by the rapidly moving strip and entrapped between the strip and the roll body surface in the holes 40.

While We have shown but one embodiment of our invention, it will be apparent that other adaptations and modifications may be made without departing from the scope of the following claims.

We claim:

1. A roll for effecting repetitive electrolytic etching of a mark of desired pattern on metal strip in traveling contact with the roll which comprises a shaft, a cylindrical roll body of electrically conductive material mounted c0- axially on said shaft, a plurality of short lengths of wire of electrically conductive material attached by one end to said roll body in radially projecting fashion arranged in the form of a desired marking pattern, and a sleeve of electrically insulating material around said roll body, the free ends of said wires being exposed and flush with the outer surface of said sleeve.

2. A roll as defined by claim 1 in which said sleeve is comprised of electrically insulating ceramic material.

References Cited UNITED STATES PATENTS 3,374,159 3/1968 Poole 204206 3,239,441 3/1966 Marosi 204224 3,152,977 10/1964 Bartholomew et al. 204224 JOHN H. MACK, Primary Examiner S, S. KANTER, Assistant Examiner US. Cl. X.R. 204206, 279 

